package com.data.geektime.week_00;

import com.data.entity.ListNode;

// 环形链表
public class Solution141 {

  // 快慢双指针
  public boolean hasCycle(ListNode head) {
    if (head == null || head.next == null) {
      return false;
    }

    ListNode slow = head;
    ListNode fast = head;

    while (fast != null && fast.next != null) {
      slow = slow.next;
      fast = fast.next.next;
      if (slow == fast) {
        return true;
      }
    }
    return false;
  }
}
